<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

</head>
<body>
    手机号码：<input type = "number"> <button>发送</button>
    <script>
        var btn = document.querySelector('button');
        var time = 10; //定义剩下的秒数
        btn.addEventListener('click', function(){
            btn.disabled = true;
            var timer = setInterval(function(){
               if(time == 0){
                //清楚定时器和复原按钮
                clearInterval(timer);
                btn.disabled = false;
                btn.innerHTML = '发送';
                time = 10;
               }else{
                btn.innerHTML = '还剩下' + time + '秒';
                time--; 
               }
            }, 1000);
        })
    </script>
</body>
</html>